Renewable fuse



4 Sept. l5, 1925` 1,554,181

A. F. DAUM RENEWABLE FUSE Fl'd Jan. 14, 1921 Patented Sept. 15, 1925.

PATENT OFFICE.

UNITED STATES AI/BERT F. BAUM, OF PITTSBURGH, PENNSYLVANIA; ROBERT E. DAUM, ADMINISTRA- TOR OF SAID ALBERT E. DAUla, DECEASED, ASSIGNOR, BY MESNE ASSIGNMENTS, TOv DAUM FUSE ANI) ELECTRIC MANUFACTURING COMPANY, OF PITTSBURGH, PENN- SYLVANIA, A CORPORATION OF PENNSYLVANIA.

RENEWABLE FUSE.

Application filed January 14, 1921.

T all 107mm it may concern.'

Be it known that I, ALBERT F. DAUM, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Renewable Fuses, of which the following is a specification.

This invention relates to improvements in renewable fuses, pertaining more particularly to structures of this type employing` the fusible element in the form of a strip or strips.

rllhe present invention embodies several characteristic features among which are the following:

(c) rlhe fusible element, in strip form, is not doubled or bent but extends in practically a single plane throughout its length; this enables the use of a construction in which the element of proper length can be positioned without removing both end structures of the fuse.

The fuse clamping action is exerted r in directions substantially transverse to the axis of the fuse rather than in the direction of length of the fuse; this makes possible a construction in which a plurality of fusible elements may be arranged within the fuse, if desired, without requiring a complicated supporting formation for the elements.

(c) rlhe ends of the fusible elements are supported in members having the characteristie of a plug for the end of the fuse casing, the member being slitted to receivev the fusible element or elements, with the slits extending in the direction of the member axis and exposed at the end of the fuse; as a result the slits and fusible element may be readily inspected to determine correctness as to loaded capacity, as well as to readily determine if the element has blown or not.

(CZ) The fusible element clamping structure may be metallic or may be of insulating material, the general arrangement of the fuse being such that either metal or insulating material may be employed in the manufacture; as a result the fuse may, with the exception of the fusible element or elements, be wholly of insulating material, or it may have one or more .of the elements Ollned of metal,

Serial No. 437,140.

(e) The fusible-element clamping member and casing are both detachably secured to the ferrule independently of each other, with the clamping member and casing formed to prevent relative rotative movement of material extent while permitting relative endwise movement; consequently, the connection between clamping member and casing may become loosened-as by shrinkage of the fibre casing-without affecting the connection between ferrule and clamping member; since the clamping action is transverse rather than longitudinal, slight looseness caused by shrinkage is ineffective to disturb the clamped relation.

(7E) The fuse may carry protective devices for the metallic portionswhere the latter are employed-these devices serving to proteet the metallic parts from the effects of the blowing of the fusible element.

(g) rThe fuse is fool-proof in that the slits of the clamping member are of definite width and insufficient to receive a fusible element of greater thickness than such width, the presence of a strip of greater width being effective to` prevent the ferrule being secured properly in position; the slits being exposed at the ends so that the end, at least, of the element is exposed, the crosssectional length of the element can be readily determined. In other words, the end of the fuse carries in exposed position, a formation which exposes each of the dimensions of a cross-section of the fusible element therein, the result being that overloading of the fuse is readily detected by simply examining the end of the complete fuse, the fusible element itself, rather than any stamped rating thereon, indicating the size characteristic of the element.

(7b) The fuse requires no manipulating instruments or tools to remove a blown fusible element or to substitute another for such fusible-element.

Other objects of the invention are to provide a construction which is simple and efficient in operation, durable in construction, which can be manufactured at relatively low cost, and which can be maintained in service at small cost.

To these and other ends, the nature of which will be readily understood as the invention is hereinafter more fully disclosed,

said invention consists in the improved construction and combination of parts hereinafter more fully described, illustrated in the accompanying drawings, and more particularly pointed out in the appended claims.

In the accompanying drawings, in which similar reference characters indicate similar parts in each of the views,-

Figures 1, 1a and 1b are views, partly in section and partly in elevation, showing` the present invention as embodied in fuse structures of different types ditiiering trom each other generally in formations other than those specifically embodied in the present invention.

Fig. 2 is a View looking at the inner end of one form of clamping member.

Fig. 3 is a similar view looking at the opposite end.

Fig. t is a view illustrating a clamping member adapted to clamp a pair of 'fusible elements with the elements having various relations to one another, the clamping member being shown in cross section.

Figs. 5 and 6 are views ot the character of Fig. 1, showing the clamping member arranged to carry a greater number of fusible elements.

In the drawing, the casing 10, preferably of insulating material, is tubular in torm and of suitable length, the ends ot the tube being open, each end preferably having a recess 1()a extending in the direction of length ot the casing, the length ot the recess. being suTicient to receive a projection presently described; in practice, I prefer to provide a length of recess such that when the ferrule 11 is in its active position it will overlie this recess, although this is not an absolute essential.

The terrule 11 and casing 10 are connected together in suitable manner, a preferred arrangement being by a threaded connection, the casing being externally threaded at its ends, the ferrule being internally threaded, the threaded portion ot the terrule being preferably of greater length than the threads of the casing, the additional threads of the ferrule being adapted to be engaged by the external threads of a clamping member 12, the latter being the member designed to carry the fusible element or elements 13.

Member' 12 is preferably formed with a reduced portion 122L which is adapted to freely enter the end of casing 10, said portion carrying the projection which enters recess 10, this projection being provided in suitable manner as by a pin 12h; the projection is preferably of less width than the width of the recess 10 thus permitting ot a limited'movement of member 12 in a rotative direction to permit adjustment ot the blades of the fuse, when the ituse is of that type. The outer end of member 12-the blade .being considered as an extension ot the member-is formed tapered with a longitudinal section contour ot' this portion extending on a straight line or on a curved line, as may be desired, the vperijgiheral contour, however, being circular; this portion ci the` member is indicated at 12e. The blade, when employed, is indicated at 111.

The errule carries an internal tace 11ZL complemental to the tace 12, these iaces having relative contours such that iu presence o1 a relative movement of the terrule and member 12 in the direction to thread the member into the` terrule, continued movement will tend to set up a pressure characteristic on the clamping member through the operation of tace 11". And since member 12 is formed with longitudinal slits 12d for the insertion or passage of the fusible element or elements, it will be understood that such pressure application will be eliective to tend to decrease the width ot the slit or slits 121 as the relative threading action is continued, so that it the fusible element be located in the slit, it will be clamped by the walls ot the slit. The slits 12d extend inwardly from the periphery ot the member-preferably in a non-radial directionso that the material ott' the member can bc sprung sufficiently to provide this clamping action.

1n this latter connection 1 prefer the width ot the slits 12(l to he substantially equal to the thickness of the fusible clement, the width being sutiicient to permit the 'lusible element to pass in the direction ot length ot' the member 12 when moved by the lingers-having the general characteristics ot' a loose tit-so that in presence ot a pressure application such as is provided by the coactingl faces 11a and 12C the springingl ol the material will produce un ctlicicnt clamping action and which will be readily released by the unthreading movement ot the terrule.

Slits 12d extend throughout the length ot member 12, and since the ierrule is preterably provided with an open end, it will hc readily understood that the ends ot the tusible element are exposed, either actually, where the element is oi? srdiicient length, or by looking into the ends o1 the slits where the element is ot less lengtl'i than the overall length ot' the fuse. And since the slits approximate the thickness ot the fusible element it will be readily understood that a fusible element ot a higher rating and hence ot greater thickness can not be readily employed, since any attempt to position such thicker fuse must provide for outward pressure on the parts ot member 12, the result being` that the periphery ot the member is expanded beyond that designed to enter the it'errule. By this means the fuse is made Lore or less Yfool-prooi?, this being due to the tact that pressure application is in a direction langular to the direction oit length. ot

the fuse, and hence the constant dimension characteristic of the ferrule can be made the element which controls the selection of the fusible element capable of use with a clamping member the slits of which are properly prepared.

As shown in the drawings, the invention is usable either with or without blade contacts. Vhere the blade contact form is employed, the clamping member, blade and ferrule may be of metal, or either or all may be of insulating material, if desired; in the latter case, the fusible element or elements have a length suflicient to cause the ends to overlie the blades, so that contact with the clip is by the fusible element itself. IVhere the blade form is not used, I prefer to have the ferrule and clamping member of metal, since the ferrule then becomes the member in Contact with the clips.

If desired, a protecting member 15 can be positioned on the fusible element inside the clamping member, the protecting member being of insulating material, thus placing a barrier to protect the clamping member from the effects of the blowing action of the fuse.

As shown in Figs. 4 to 6, the slits of the clamping member may be provided in a number of different formations. For instance, forms d, e and f indicate various ways in which the slits 12d can be arranged to provide for the use of two fusible elements; it will be understood that one of the slits of either form d or e may be used if lthe member is designed to carry a single element, if in blade form and it be desired to have the element overlie the blade. In F ig. 5, forms g and h indicate ways in which a member carrying three fusible elements may be provided. Fig. 6 shows an arrangement for four fusible elements.

rFliese are more or less representative of various forms in which the slits may take,

the invention not being limited in this respect, the general characteristic being the formation of a slit which extends inward from the periphery of the member in such direction that under the clamping action set up by faces 11a and 12C the material of at least one side of the slit will shift under the pressure sufficient to set up the clamping action; this characteristic will tend to prevent the use of radial slots, although, as shown in form g, this is not true in all cases.

As will be understood, but one end of the fuse need be removed to provide for renewal, this not being absolutely essential, but desirable since it permits of a readier entry of the fusible element into the slot. The clamping member with the fusible element or elements therein, is then positioned at the end of the casing and the ferrule threaded on to the clamping member--held against rotation by pin 12b-and then on to the casing. There the parts are metal, it will be obvious that shrinkage of the fibre casing to loosen the threaded connection with the ferrule will not affect the clamping action, that action remaining constant since it is necessary to set up rotative action between ferrule and clamping member to affect this connection.

As heretofore pointed out, various parts of the structure may be formed of either metal or of insulating material, the difference in this respect being simply that of material. For this reason, the description refers generally to but one material for clearness. In the drawings, however, there is more or less distinction made by different reference characters. For instance, the ferrule, when of metal, is indicated at 11, and when of insulating material, it is indicated at 11; similarly, its internal face is indicated at 11a in the metal form, and as 11a in the insulating material form. Likewise, the blade form of the clamping member, when of metal, is indicated at 12, while the insulating material form is indicated at 12'; to further distinguish in this respect, the form of the clamping member which omits the blade is indicated at 12".

This variation in reference characters, however, is not intended to indicate any differences other than those referred to. The form of the ferrule is the same regardless of material; and this is 'true with respect to the clamping member, excepting with respect to the presence or omission of the blade-the member 12" for instance having the blade removed-and the possible difference in position of the slits 12d, as indicated in the different figures. For instance, the member of Figs. 4 to 6 may be considered as either 12, 12 or 12 in type.

Thile I have herein shown and described several ways in which my invention can be carried into effect7 it will be readily understood that changes and modifications therein may be found desirable or essential in meeting the various eXigencies of use, and I desire to be understood as reserving the right to make any and all such changes or modifications therein as may be found desirable or necessary, in so far as the same may fall within the spirit and scope of the invention as expressed in the accompanying claims when broadly construed.

Having thus described my invention, what I claim as new is:

1. In a renewable fuse, a tubular casing of insulating material, a clamping member positioned at the end of the casing and projecting therebeyond, a ferrule removably secured to the casing and such member, said member being slitted in the direction of the member axis to receive a fusible element, said member and ferrule having complemental means operative to provide clamping action on the fusible element by the slit walls.

2. A fuse as in claim 1 characterized in that the clamping member is exposed at the end of the fuse, and that the outer end of the ferrule and of the clamping member face extend on substantially the same plane when the fusible element is clamped in po- Sition.

3. A fuse as in claim 1 characterized in that the clamping member slit arrangement is exposed at the end of the fuse, and that the outer end of the ferrule and of the clamping member face extend on substantially the same plane when the fusible element is clamped in position.

4. A fuse as in claim 1 characterized in that the clamping member is held against longitudinal and rotating` movement during the clamping operation, and that the normal width of the member slits approximates the thickness of the fusible element.

5. A fuse as in claim 1 characterized in that the clamping member is exposed at the end of the fuse with the area of exposure sufficient in dimensions to permit positioning of the fusible element through such exposed portion, and that the outer end of the ferrule and of the clamping member face extend on substantially the same plane when the fusible element is clamped in position.

6. A fuse as in claim 1 characterized in that the casing and clamping member are relatively formed to prevent relative rotation thereof in excess of an angular distance of 90o, the formation being positioned to locate it in a zone of the member spaced longitudinally from the clamping zone of the member.

7. A fuse as in claim 1 characterized in that the clamping member and casing carry complemental means to permit relative movement therebetween in an endwise direction and prevent rotative movement in excess of 90, said means being located in spaced relation to the clamping zone of the member.

8. A fuse as in claim l characterized in that the casing is provided with a recess extending inward from an end thereof, the member havinga projection adapted to enter `said recess, the projection being located spaced from the clamping zone of the member.

9. A fuse as in claim 1 characterized in that the casing is provided with a recess extending inward from an end thereof, the clamping member having a portion extending into the casing and carrying a projection adapted to enter the recess, the projection being located spaced from the clamping -zone of the member.

10. A fuse as in claim 1 characterized in that the casing is provided with recess extending inward from an end thereof, the member having a projection adapted to enter said recess, the ferrule overlying such recess when in operative position, the projection being located spaced from the clamping zone of the member.

11. A fuse as in claim 1 characterized by a protecting member of insulating material mounted within the casing beyond the inner face of the clamping member.

12. In renewable fuses, a casing, means for removably securing a fusible element of strip form in position at the end of the casing, said means including a clan'iping member slitted to receive the strip, and a member having an annular formation operative on the clamping member to produce clamping of the strip by the slit walls, said member being adapted to overlie the casing end when the fuse is assembled.

13. In renewable fuses, means for removlably securing a fusible element of strip form in position at the end of the fuse, said means including a clamping member having a slitted portion with the direction of length of a slit extending in the direction of fuse axis, and a member having an annular wall secured to the periphery of the clamping member and having a face operative on the clamping member to produce clamping of the strip by the slit walls.

111. Means as in claim 12 characterized in that the two members have a threaded connection.

15. Means as in claim 12 characterized in that the two members have complemental annular faces adapted to set up a wedging action upon the clamping member.

16. Means as in claim 12 characterized in that the two members have complemental threaded faces and carry complementa-l anw nular faces adapted to set up a wedging action on the clamping member by the threading movement of one member relative to the other.

17. A renewable fuse adapted to carry a fusible element of strip form, said fuse comprising a casing, and an instrumentality at each end of the casing adapted to clamp the strip ends, each instrumentality including a clamping member and an annular element overlying the periphery of the casing end and active to apply clamping pressure on the clamping member in a direction transverse to the axis of the fuse.

18. A fuse as in claim 17 characterized in that the clamping member is slitted in the direction of its axis, with the slit walls acting on the fusible element in the clamping operation.

19. A fuse as in claim 17 characterized in that the instrumentality includes a clamping member carrying a blade, said member being slitted in the direction of its axis to permit location of the fusible element within the slit and project into overlying relation to such blade.

20. A fuse as in claim 17 characterized in that the annular element is co-operative with a clamping member slitted in the direction of its axis, With the slit Walls active in the clamping operation, said member carrying a blade exposed at the end of the fuse, said slitted portion being positioned to permit the fusible element to project from the slitted portion into overlying relation to the blade.

2l. A clamping member for fuses, said member having a configuration to be removably secured at the end of a casing and carrying a longitudinal slit throughout its length7 with the slit extending from the periphery inward in a direction to permit relative movement of the slit Walls to apply clamping pressure on a fusible element located Within the slit.

22. A member as in claim 21 characterized in that the normal Width of the slit approximates the thickness of the fusible element strip.

23. A member as in claim 21 characterized by a plurality `of independent slits each extending longitudinally and positioned relatively to each other and to the peripheral contour in a manner to permit concurrent pressure application on individual fusible elements Within the respective slits.

In testimony whereof7 I have hereunto afliXed my signature.

ALB ERT F. DAUM. 

